Holding cabinets, methods for controlling environmental conditions in holding cabinets, and computer-readable media storing instructions for implementing such methods

ABSTRACT

A holding cabinet includes a body defining a holding space and a holding compartment disposed within the holding space for holding a product therein. The holding cabinet further includes a heating source, a steam generator, a temperature sensor, a humidity sensor, a product detector, and a controller. The controller is configured to regulate environmental conditions of the holding compartment according to a determined setpoint, which corresponds to a predetermined temperature and relative humidity. The controller regulates such environmental conditions by acquiring the sensed air temperature, relative humidity, and the detected type of product, and activating and deactivating the heating source and the steam generator in accordance with the acquired air temperature, relative humidity, and the determined setpoint corresponding to the type of product detected and a holding time of the product, to maintain the air temperature and the relative humidity within a predetermined range based on the determined setpoint.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationSer. No. 61/945,069, filed Feb. 26, 2014, which is incorporated byreference herein in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a holding cabinet, which provides amore consistent and accurate holding environment for food products. Inparticular, the invention relates to a holding cabinet, which provides amore consistent and accurate holding environment for food products byproviding control of environmental conditions within the cabinet.

2. Description of Related Art

There is a demand for food holding devices that maintain food productsat a substantially uniform temperature for selected periods of timewhile preserving the taste, moisture content, texture and quality of thefood. Further, in other applications, it is desirable to be able torestore food products to acceptable quality after long storage periods.

Holding cabinets for cooked food products provide an environment inwhich certain environmental variables may be controlled to some degree.For example, air temperature may be controlled to a particulartemperature level in an attempt to maintain the food product in ajust-cooked state until it is served. These variables affect the qualityof the food products. Several food product parameters are important tomaintain food product quality. These product parameters includetemperature, moisture content, color and texture. Texture is a complexcombination of olfactory and gustatory sensations, which in turn arecreated by the mechanical and chemical properties of the food beingheld.

The initial food product parameters described above are primarilydetermined by the food product composition and the cooking process, butduring holding, they are changed by the holding environment parameters.Exemplary environment parameters include air temperature, relativehumidity, and airflow. Airflow can be considered as the mean speed atwhich air moves over the food product. Other environment parametersinclude heat conducted into the food product and radiant energy appliedto the food product.

Previously, various methods and devices have been developed to attemptto maintain heat and humidity. These devices and methods, however,suffer from drawbacks such as high airflow and inaccurate temperatureand humidity control. High airflow levels are detrimental to foodquality over long periods. The airflow increases evaporative coolingfrom the food product, which causes the food product to cool excessivelyas well as reducing the moisture content below an acceptable level.Current holding cabinets may give acceptable results for short holdingtimes, if the proper holding parameters are established and the cabinetcan maintain the parameters within acceptable limits. Nevertheless,environmental parameters are not well controlled and holding times arelimited before the quality of food products deteriorates below anacceptable level. More particularly, it has been found that aircirculation characteristics and improper storage temperature contributesignificantly to bacteria growth and excessive loss of moisture whichleads to food shrinkage, so that in an improper storage atmosphere, thefood deteriorates after only a short period of time and loses itstenderness, appetizing taste, and appearance. It has also been foundthat even where food is stored under favorable conditions in anenclosure, the food deteriorates at a rate dependent on the time thedoor to the enclosure is opened, exposing the storage chamber to theambient atmosphere.

Additionally, it is known that in storage of some foods, such as friedchicken or fish, where a crust is provided, it is particularly desirableto maintain the crispness of the crust while minimizing the moistureloss from the underlying meat. Storage of such foods tends to involvethe satisfaction of seemingly mutually exclusive conditions, to hold thecrispness of the crust by maintaining low moisture content in the crustwhile minimizing moisture loss from the food. In such foods, excessivemoisture-loss results in shrinkage and loss of tenderness and adverselyaffects the texture of the meat. This may be prevented by controllingthe temperature and humidity of the storage atmosphere. The problem ispreventing moisture flow from the underlying food to the crust whileholding the crust in low moisture content.

SUMMARY OF THE INVENTION

Therefore, a need has arisen for holding cabinets for attainingenvironmental control by means of one or more environmental sensors andone or more controllers configured to adjust environmental conditionswithin such holding cabinets based on readings from the one or moreenvironmental sensors. Consequently, in particular configurations ofcabinets disclosed herein, such cabinets may comprise one or more of atemperature sensor, a humidity sensor, and airflow sensor, and thecontrol systems of such cabinets may utilize the readings from suchsensors to adjust one or more of the temperature within a cabinetchamber, the humidity within the cabinet chamber, and the flow of airwithin the cabinet chamber (e.g., environmental conditions within thecabinet), such that the environmental conditions within the cabinetextend the holding time for food products stored within the cabinetchamber before significant degradation in quality of the food productsoccurs (e.g., noticeable changes in taste, texture, or tenderness, orsignificant bacterial growth). Accordingly, such cabinets may implementa feedback loop to ensure that the environmental conditions within thecabinet are maintained within a predetermined range. Such apredetermined range may be a particular combination of environmentalconditions (e.g., temperature, humidity, and airflow) that extends theholding time for food products, before significant degradation inquality occurs, compared to other combinations of the environmentalconditions.

Moreover, different food products may possess different materialproperties. Therefore, a further need has arisen to maintain theenvironmental conditions within the cabinet in a predetermined range,specific to a particular food product, such that the holding time of theparticular food product, before the quality of the particular foodproduct degrades significantly, is extended. Consequently, in certainconfigurations of cabinets disclosed herein, the control systems of suchcabinets may store and implement different predetermined ranges ofenvironmental conditions for different types of food products. Methodsdisclosed herein may be methods for maintaining environmental conditionsin a cabinet. Computer-readable instructions to perform such methods maybe stored on non-transitory, computer-readable media and implemented byone or more processors, e.g., CPU, ASIC, or the like. Further, a systemcomprising a processor and a memory storing such computer-readableinstructions may implement such methods.

In an embodiment, a holding cabinet comprises a body defining a holdingspace and a holding compartment disposed within the holding space andconfigured to hold a product therein. The holding cabinet furthercomprises a heating source; a steam generator in atmosphericcommunication with the holding compartment and configured to generatesteam; a temperature sensor disposed adjacent to the holding compartmentand configured to measure an air temperature of the holding compartment;a humidity sensor disposed adjacent to the holding compartment andconfigured to measure a relative humidity of the holding compartment; aproduct detector configured to detect that a product is loaded in theholding compartment and to identify a type of the product; and acontroller. The heating source comprises one or more of: a radiantheater disposed above the holding compartment, a conduction heaterdisposed below the holding compartment, and a convection heater disposedat an end of the holding compartment. The controller is configured toregulate environmental conditions of the holding compartment accordingto a determined setpoint, which corresponds to a predeterminedtemperature and relative humidity. The controller is configured toacquire the air temperature sensed by the temperature sensor, therelative humidity sensed by the humidity sensor, and the type of productdetected by the product detector. In accordance with the acquired airtemperature, the acquired relative humidity, and the determined setpointcorresponding to the type of product detected and a holding time of theproduct, the controller is further configured to activate and deactivateone or more of the radiant heater, the conduction heater, the convectionheater, and the steam generator to maintain the air temperature and therelative humidity of the holding compartment within a predeterminedrange based on the determined setpoint.

In an embodiment, a method for regulating environmental conditions of aholding cabinet, comprises sensing an air temperature in the holdingcabinet with a temperature sensor; sensing a relative humidity in theholding cabinet with a humidity sensor; and detecting a type of productin the holding cabinet with a product detector. According to adetermined setpoint that corresponds to a predetermined temperature andrelative humidity, the method also comprises activating and deactivatingone or more of a radiant heater, a conduction heater, a convectionheater, and a steam generator to maintain the air temperature and therelative humidity within a predetermined range based on the determinedsetpoint in accordance with the sensed air temperature, the sensedrelative humidity, and the determined setpoint corresponding to the typeof product detected and a holding time of the product.

In an embodiment, a computer readable program product storesinstructions that, when executed by a processor, instruct the processorto perform processes comprising: sensing an air temperature in theholding cabinet with a temperature sensor; sensing a relative humidityin the holding cabinet with a humidity sensor; detecting a type ofproduct in the holding cabinet with a product detector. According to adetermined setpoint that corresponds to a predetermined temperature andrelative humidity, the processes further comprise activating anddeactivating one or more of a radiant heater, a conduction heater, aconvection heater, and a steam generator to maintain the air temperatureand the relative humidity within a predetermined range based on thedetermined setpoint in accordance with the sensed air temperature, thesensed relative humidity, and the determined setpoint corresponding tothe type of product detected and a holding time of the product.

Other objects, features, and advantages of the present invention will beapparent to persons of ordinary skill in the art in view of thefollowing detailed description of embodiments of the invention and theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the embodiments of the presentinvention, needs satisfied thereby, and the objects, features, andadvantages thereof, reference now is made to the following descriptiontaken in connection with the accompanying drawings.

FIG. 1 depicts a perspective view of the holding cabinet according to anexemplary embodiment of the present invention.

FIG. 2 depicts a front view of the holding cabinet according to anexemplary embodiment of the present invention.

FIG. 3 depicts a front perspective view of the holding cabinet accordingto an exemplary embodiment of the present invention.

FIG. 4 depicts a cut-away side view of the holding cabinet according toan exemplary embodiment of the present invention.

FIG. 5 depicts a radiant heater for the holding cabinet according to anexemplary embodiment of the present invention.

FIG. 6 depicts a cut-away view of the holding cabinet according to anexemplary embodiment of the present invention.

FIG. 7 depicts a convection heater for the holding cabinet according toan exemplary embodiment of the present invention.

FIG. 8 depicts a partial view of the holding cabinet according to anexemplary embodiment of the present invention.

FIG. 9 depicts a partial view of the holding cabinet according to anexemplary embodiment of the present invention.

FIG. 10 depicts a block diagram of the holding cabinet control systemaccording to an exemplary embodiment of the present invention.

FIG. 11 is a schematic of a controller that may control operations ofthe holding cabinet.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Exemplary embodiments disclosed herein may, for example, reduce wasteand improve profits by extending the useable life of food. In particularconfigurations, methods and systems disclosed herein may optimize theholding variables, including holding temperature and relative humiditywith controllable equipment.

Further, embodiments disclosed herein may allow for a plurality of setpoints (e.g., different temperatures, humidity values, and airflowrates) that may each correspond to a particular product type or categoryto be held in the cabinet (e.g., the inventors have determined that thelife of different products may be extended, but such extensions mayrequire different settings for each different food product). Inaddition, the invention disclosed herein may extend product quality fora longer time while product is being held in the cabinet.

Still further, in certain configurations, the invention disclosed hereinmay optimize the combination of the variables for better productquality. In addition, systems disclosed herein may quantify sensoryattributes in a manner that permits fine tuning and adjustment ofenvironmental conditions and extend the life of held food products.

Embodiments of the present invention, and their features and advantages,may be understood by referring to FIGS. 1-11, like numerals being usedfor corresponding parts in the various drawings. While process stepsdisclosed herein are described in an exemplary order, the invention isnot so limited, and the process steps described herein may be performedin any order. Further, one or more of the process steps may be omittedin certain configurations.

Referring to FIGS. 1 and 2, a perspective view of the holding cabinetand a front view of the holding cabinet according to an exemplaryembodiment of the present invention are provided, respectively. Holdingcabinet 100 includes an enclosure 105 including a front 102, a back 104,and sides 106 and 108. Front 102 and back 104 may both have at least onedoor or may be open (i.e., a closed or open holding cabinet system). Inthe embodiment shown in FIGS. 1 and 2, front 102 is open and back 104 isclosed.

FIG. 1 shows holding cabinet 100 with an upper holding compartment 120and a lower holding compartment 130. In addition, four product holdingtrays 115 are shown inserted in a holding position. FIG. 1 shows threetrays 115 in lower holding compartment 130 and one tray 115 in upperholding compartment 120. A side vent 148 is also shown on side 108 ofholding cabinet 100 disposed near back 104. As shown in FIG. 2, a sidevent 146 may be disposed on side 106 in a similar location as vent 148positioned on side 108 (i.e., opposite to each other). Conductionheating elements 140 may be mounted to the lower surfaces of each of theupper holding compartment 120 and lower holding compartment 130. Theheat generated from conduction heating elements 140 may be conductedfrom the heating element portions, through product holding tray 115, andto the food product held within product holding tray 115.

FIG. 2 shows six product holding trays 115 in a holding position withinholding cabinet 100. Three product holding trays 115 may be disposed inupper holding compartment 120 and three product holding trays may bedisposed in lower holding compartment 130. In alternative embodiments,each holding compartment may be configured to hold either more than orless than a maximum of three holding trays 115. Further, holding cabinet100 may be configured to have either more than or less than two holdingcompartments.

FIG. 3 shows a front perspective view of the holding cabinet accordingto an exemplary embodiment. Three product holding trays 115 are shown inlower holding compartment 130, with no trays shown in upper holdingcompartment 120. As shown in FIG. 3, radiant heaters 145 may be disposedabove the positions of product holding trays 115 in each of upperholding compartment 120 and lower holding compartment 130. Thus, forexample, a radiant heater 145 is disposed above respective positionswhere each product holding tray 115 is held in the holding position inholding cabinet 100. Alternatively, more than one radiant heater 145 isdisposed above respective positions where each product holding tray 115is held in the holding position in holding cabinet 100. Further, thenumber of radiant heaters 145 disposed above respective positions whereeach product holding tray 115 is held in the holding position may beuniform or non-uniform (i.e., each may have the same or a differentnumber of radiant heaters 145).

Thus, radiant heaters 145 may be mounted to the upper interior surfaceof each of upper holding compartment 120 and lower holding compartment130. Accordingly, radiant energy may be directed to the food productbeneath the elements of radiant heaters 145 while held in holdingcabinet 100.

FIG. 4 shows a cut-away side view of holding cabinet 100 according to anexemplary embodiment. A convection heater 150 is shown near back 104side of holding cabinet 100. Convection heater 150 may include aconvection blower motor 152, a convection heating element enclosure 154enclosing a convection heating element 156 (shown in FIG. 7), and aconvection heat mixing chamber 180. The convection heating system mayinclude a single convection heating element 156 combined with adistribution fan or blower 157 driven by convection blower motor 152.The heated air may be distributed to each of the holding compartments ofholding cabinet 100 through ducting channels. Fan or blower 157 alsocontrols airflow through the holding compartments. Further, a ventingsystem having vent openings (e.g., vents 146 and 148) may be provided,which may be operated to remove air from the holding compartments ofholding cabinet 100.

FIG. 5 shows radiant heaters 145 for one of the holding compartments ofholding cabinet 100 according to an exemplary embodiment. Radiantheaters 145 may include radiant heating elements 146 that extendlongitudinally in the front-to-back direction. The generated radiantheat may be directed downward through openings toward food product heldin holding cabinet 100 to heat the food product.

FIG. 6 shows a cut-away view of the holding cabinet according to anexemplary embodiment. A steam generation system 160 may be disposed on aside near back 104 of holding cabinet 100. Steam generation system 160may include a steam generator 162, a water inlet 164, through whichwater enters steam generator 162 from a water source, and steam outlet166, through which steam is emitted to a manifold or convection heatmixing chamber 180. In this manner, the humidity of the air in holdingcabinet 100 may be increased and dynamically controlled. Other means ofproviding humidity, such as a mister, are also suitable for use with thepresent disclosure.

FIG. 7 shows convection heater 150 for holding cabinet 100 according toan exemplary embodiment. Convection heater 150 may include a convectionheating element 156 and a fan or blower 157. Convection heater 150 maybe disposed on or near back 104 of holding cabinet 100. Fan or blower157 may blow air heated by convection heating element 156 into theholding compartments of holding cabinet 100. Further, fan or blower 157may be used to generally control airflow in holding cabinet 100.

FIG. 8 shows a partial view of the holding cabinet according to anexemplary embodiment. In order, from back 104 towards front 102, holdingcabinet 100 may include convection blower motor 152, convection heatingelement enclosure 154 enclosing a convection heating element 156, andconvection heat mixing chamber 180. Convection blower motor 152 may bemounted on convection heating element enclosure 154, which is inatmospheric communication with convection heat mixing chamber 180.

FIG. 9 shows a partial view of the holding cabinet according to anexemplary embodiment. As an alternative to steam generator 162 shown inFIG. 6, a “hot plate” type steam generator 190 may be provided inholding cabinet 100. Steam generator 190 may be mounted under or nearthe bottom of convection heat mixing chamber 180. Steam generator 190introduces water into the air through a process of heating water storedin a reservoir to produce steam.

FIG. 10 shows a block diagram of system 300 according to an exemplaryembodiment. System 300 may include a controller 301. System 300 mayinclude air temperature sensor 302 that measures the temperature of theair in the holding cabinet. Air temperature sensor 302 may also be usedto provide temperature compensation for humidity sensor 304. Humiditysensor 304 may measure the relative humidity of the air in holdingcabinet 100. One or more of conduction heating elements 140, radiantheaters 145, and convection heater 150 may heat the air in holdingcabinet 100 to a specified set point corresponding to desiredenvironmental conditions. Fan or blower 157 may circulate heated airthrough the cabinet to regulate temperature and/or air flow.

System 300 also may include at least one airflow sensor 306 thatmeasures the rate of airflow in holding cabinet 100. Such an airflowsensor 306 may be disposed anywhere in holding cabinet 100, such as, forexample, near or at an entry point where air is blown into the holdingcompartments, air temperature sensor 302, humidity sensor 304, a centrallocation in holding cabinet 100, or any combination thereof. Further, aplurality of airflow sensors 306 may be disposed through the cabinet inorder to determine an average rate of airflow.

System 300 may further include one or more door switches 310 disposed onor near a door or flap of a closed type of holding cabinet. Controller301 may use input from door switch 310 to detect when a door is open andmay energize the heating and/or steam generation systems to maintain thetemperature and humidity at the desired set points.

The cabinet air temperature can be regulated with air temperature sensor302, fan or blower 157, and one or more of conduction heating elements140, radiant heaters 145, and convection heater 150. The air temperatureregulation comprises regulating the air temperature to the specified setpoint, which may be accomplished through known temperature regulationsystems and processes. Temperature regulation may be accomplished with,for example, a more simple thermostatic (on/off) control with hysteresisor a more sophisticated PID (proportional/integral/derivative) controlalgorithm.

Humidity may be regulated by 1) adding humidity when the humidity inholding cabinet 100 is below the humidity set point; and 2) decreasinghumidity by introducing outside ambient air to holding cabinet 100, whenthe humidity in holding cabinet 100 is above the programmed set point.Thus, there may be at least two separate systems to regulate thehumidity: a humidity generation system, and a venting system. Airflowmay be regulated by 1) adjusting the speed of fan or blower 157, and 2)opening and closing vents in the venting system to permit entry ofoutside ambient air into holding cabinet 100 and escape of interior airfrom holding cabinet 100. When fan or blower 157 is activated, air fromoutside the cabinet may be injected into holding cabinet 100, for themost part, preventing the humidity in holding cabinet 100 from exceedinga predetermined level. Thus, according to an exemplary embodiment,humidity control comprises three states: Idle, Increase Humidity, andDecrease Humidity.

In particular configurations, a memory may store a plurality of setpoint values, each of which may correspond to a predetermined range,within which at least one of the temperature, the humidity, and theairflow rate in the holding cabinet is to be maintained. In someconfigurations, each set point value, and each predetermined rangecorresponding to the set point, may be associated with a particular foodproduct and may be associated with a timing or time period in theholding time. In this manner, the environmental conditions for differentfood products, having different material properties, may be maintainedin a manner particularly suited for that product throughout the holdingtime, and thus, extends the holding time before significant degradationof that product's quality occurs. For example, one set point isassociated with chicken nuggets, while another set point is associatedwith churros. In this manner, the system may use an appropriate setpoint for a particular food product to further extend the holding timefor that particular food product before significant degradation ofquality occurs, after the system determines the type of the particularfood product held or to be held in the holding cabinet. Moreover, eachfood product may have a particular set of set points distributed throughthe duration of the holding period, which accounts for differentenvironmental conditions desired for different times during the holdingperiod of the particular food product.

Thus, in certain configurations, the memory stores a plurality of setpoint values which may be utilized at different times during the holdingprocess. For example, one set point may be utilized for the first fiveminutes of holding, and another set point may be utilized for theremainder of the holding period. In still other configurations,different set points are utilized upon the occurrence of differentevents. For example, one set point may be utilized when the food productis initially placed in holding cabinet 100, and another set point may beutilized when a cabinet door is opened or a tray is removed.

Holding cabinet 100 may include a controller 200 disposed therein. Inother configurations, controller 200 is external to holding cabinet 100.As shown in FIG. 11, controller 200 may include a process control unit(“PCU”) 210 and a memory 220. Memory 220 may be a non-transitory memorydevice, examples of which may include: one or more of a solid statedrive, a hard drive, a random access memory, read-only memory, or othermemory device, that may store computer-readable instructions forexecution by PCU 200. When PCU 200 executes the computer-readableinstructions stored in memory 220, the instructions may instruct PCU 200to control the functions of holding cabinet 100 described herein.Specifically, controller 200 may be configured to control the operationsof the components of holding cabinet 100. In some configurations, eachof a plurality of controllers 200 controls a different operation orcomponent of holding cabinet 100. Controller 200 may comprise one ormore PCUs 210.

Configurations of the holding cabinet may utilize a variety ofhumidity-generation means. For example, the holding cabinet may comprisea steam generator, which may generate humidity in the holding cabinet.Further, such a steam generator, for example, may be configured todischarge steam at various locations throughout the holding cabinet(e.g., positions along the sides of the holding cabinet, positions atthe top of the holding cabinet, positions at the bottom of the holdingcabinet), and steam discharge ports may be oriented to circulate steamat various angles in various directions throughout the holding cabinet.In addition, other humidity generation methods may be utilized togenerate humidity in the holding cabinet.

In particular configurations, the pattern of airflow within the holdingcabinet may be changed as part of the environmental control process inresponse to the measured temperature, humidity, and airflow rates. Suchchanges may be in addition to or in lieu of changing the airflow rate.For example, introductory air vents may be selectively opened and closedto change the pattern of airflow. In certain configurations, air isselectively introduced at different or varying angles in response to themeasured temperature, humidity, and airflow rates, which may altercirculation patterns, humidity gradients, and temperature gradientsthroughout the holding cabinet. In some configurations, air isselectively introduced in different directions (e.g., horizontal,vertical) and from different sides (e.g., top, bottom, right, left,back, front) of the holding cabinet, which also may alter circulationpatterns, humidity gradients, and temperature gradients throughout theholding cabinet. In addition, similar patterns of humidity introduction(e.g., through steam jets) also may be utilized, alone or incombination, with such airflow patterns.

In some configurations, the holding cabinet comprises a plurality ofzones (e.g., a multi-zone holding cabinet) for storing a plurality ofdifferent food products. For example, each zone of the plurality ofzones may have its own set point value, and each of the temperature, theairflow rate, and the humidity may be regulated independently in eachzone. Such zones may be defined, for example, by one or more holdingcompartments within the holding cabinet, and each holding compartmentmay be separated by a wall (e.g., a solid wall, a porous wall). Further,each holding compartment may comprise its own temperature sensor,humidity sensor, and airflow sensor, as well as its own heater, fan, andhumidity generator, so that the environmental control process may beperformed separately for each holding compartment. Alternatively, aholding compartment shares at least one of the sensors and/or at leastone of the heater, fan, and humidity generator with at least one of theother holding compartments. In other configurations, such zones aredefined, for example, by one or more virtual cabinets within the holdingcabinet, which may each be a particular region within the holdingcabinet (e.g., an upper region, a middle region, a lower region). Suchvirtual cabinets may not be physically separated from each other but mayeach comprise its own temperature sensor, humidity sensor, and airflowsensor, as well as its own heater, fan, and humidity generator, so thatthe environmental control process may be performed separately for eachvirtual cabinet. In certain configurations, such virtual cabinets maynot each comprise its own heater, fan, and humidity generator, and oneor more of air, heat, and humidity is introduced into each virtualcabinet by appropriately directing the one or more of air (e.g., airvents, which can be selectively opened and closed, angled in differentdirections to direct air to different zones within the holding cabinet),heat (e.g., creating zones requiring warmer temperatures near a heaterat the top of the holding cabinet; disposing thermal masses in each zoneto retain heat), and humidity (e.g., steam vents, which are selectivelyopened and closed, angled in different directions to direct humidifyingsteam to different zones within the holding cabinet).

An advantage of the above-described holding cabinet is its flexibilityin optimizing holding time for different product types. For example, ifa food product requires both low airflow and high temperatures, then theconvection heat system may be disabled, or run at very low power, andthe food product may be heated by the conduction and radiant heatsystems. The humidity can be regulated to any desired setpoint, sincethe steam may be injected directly into the holding area and may notrely on the convection heat fan for distribution. This differs fromexisting holding cabinets which generate steam by heating a large volumeof water in a reservoir in the bottom of the holding compartment. Thismethod suffers from the disadvantages that 1) it is difficult toregulate low humidities in the holding compartment, since some steamalways evaporates from the reservoir and 2) relatively high airflow isnecessary to equally distribute the steam through the holdingcompartment.

Some operating conditions result in excess humidity in the holdingcompartment. For example, if a large quantity of food product is loadedinto the holding compartment, the water vapor emitted by the foodproduct will increase the humidity. If the resulting humidity is toohigh, the convection heat system fan and vent may be operated to removesome humid air from the holding compartment and replace it with lesshumid air from outside the holding compartment. Some food products mayrequire relatively low holding temperatures and high humidities. Thisenvironment is easily created in the cabinet by operating only theconvection heat system and steam generation system.

The holding cabinet according to embodiments of the invention has theability to vary the holding environment parameters over the holdingtime. This is important because the properties of the held food willchange during holding. A particular set of environment parameters thatgive optimum results during the first twenty minutes may cause poorproduct quality if maintained beyond that time.

For example, a fried food product may enter the cabinet at a hightemperature. The meat portion of the food product is moist, and theouter breading is neither too crisp nor too moist. Optimal settings fortemperature and humidity to hold the food product for twenty to thirtyminutes may be determined by product testing. If the food product isheld at the same settings beyond that time, then too much water from themeat portion may travel through the breading layer. This causes the meatto dry out and cool, and the breading layer to become too crisp ortough.

Embodiments of the invention provide the capability to program the PCUto change the environment parameter setpoints as a function of the holdtime. For example, for a fried food product it may be appropriate togradually increase the humidity and decrease the airflow as the holdtime elapses. Both of these changes reduce evaporation from the foodproduct, and thus keep the meat portion moist and the breading at thedesired crispness. Since the environment parameters may be regulatedindependently, they may all be changed over the hold time to control theproduct characteristics. Accordingly, a dynamic holding environment isprovided to achieve proper environmental conditions throughout theholding time according to the food product being held.

A holding cabinet may implement hold timers. The operator may manuallystart the timer when the product tray is loaded. A display on the PCUmay show the remaining hold time. When the hold time elapses, the PCUmay emit a visual and/or audible alert to inform the operator that thehold time is expired and the product is no longer suitable for servingand should be discarded.

According to some embodiments of the invention, a holding cabinetimplements a system to automatically detect when the operator loads aproduct tray, and may further automatically detect the type of foodproduct and select regulation setpoints for the environment parameters.

A variety of methods may be used to detect that the product tray isloaded, and further identify the type of product. Detection methodsdescribed below include mechanical, optical, radio frequency (RF), andimage recognition. Regardless of the detection method, the PCU mayidentify the product type when the tray is inserted and execute twoactions in response. First, the hold timer for the tray may be started.Second, the PCU may begin regulating the environment parameter setpointsfor that particular product type, as described above with respect tovariable environment parameter regulation during holding. Thisregulation accounts for the fact that the environment parameters changeover the holding time and the product trays may be randomly loaded andunloaded. Further, isolated holding chambers may be provided for eachproduct tray.

According to mechanical detection, the product tray may be mechanicallyconfigured with notches, dimples, or detents which encode the producttype. For example, three notch locations can be used to encode eightproduct types by the presence or absence of a notch. The notches may beread by microswitches or other methods known in the art.

According to optical detection, the product tray may be tagged with alabel incorporating a bar code or other graphic device. The appropriatesensor, for example a bar code reader, may be connected to the PCU,which detects the product type accordingly.

According to RF detection, the product tray may be tagged with a radiofrequency identification device (RFID), known in the art. The PCU may beconnected to an RFID reader that reads the RFID to detect product traypresence, as well as the product type.

According to image recognition detection, the cabinet may be equippedwith one or more cameras aimed at the product tray area. The PCU may usethe images from the cameras and appropriate image processing to detectthat a tray has been inserted, and to identify the food product typefrom image characteristics such as geometry and color. For example, atray of one food product can be distinguished from a tray of a differentfood product by identifying the size and shape of the individual foodproduct pieces. The camera may operate in visible or infraredwavelengths.

Although particular configurations disclosed above may utilize afree-standing holding cabinet, other holding cabinets may be utilized.For example, the systems and methods disclosed herein may beincorporated into a portable merchandiser (e.g., a pizza deliverycontainer, another container for holding food to be delivered).Accordingly, such a portable merchandiser can be configured to performthe environmental control process and extend the holding period of“to-be-delivered” food products before the quality of such food productsbegins to degrade. Other types of holding containers also may beutilized.

In particular configurations, the environmental process, which may becontrolled by controller 200, utilizes at least one set point valuecorresponding to the type of food product held in holding cabinet 100,as well as the holding time. Specifically, controller 200 may determinethe type of product held in holding cabinet 100 and a timer may be usedto determine the holding time. For example, controller 200 may make thisdetermination based on a reading from a detector. Thereafter, controller200 may select a predetermined set point value, which is stored in amemory, such as memory 220, for the determined type of food product heldin holding cabinet 100. In particular configurations, the selectedpredetermined set point value corresponds to a value of one or more oftemperature, humidity, and airflow rate, alone or in combination, whichhas been determined to extend the holding time of the determined type offood product before its quality degrades significantly as compared toother such values of the one or more of temperature, humidity, andairflow rate, alone or in combination. In addition, the set point maycorrespond to particular ranges about the one or more of temperature,humidity, and airflow rate, which have been determined to extend theholding time of the determined type of food product before its qualitydegrades significantly as compared to other such values of the one ormore of temperature, humidity, and airflow rate, alone or incombination. In certain configurations, the set point is selectedwithout determining a product load (e.g., the amount of the food productto be held in holding cabinet 100).

Thereafter, the holding process may start. During the holding process,humidity sensor 304 may measure the humidity of the air in holdingcabinet 100, air temperature sensor 302 may measure the temperature ofthe air in holding cabinet 100, and airflow sensor 306 may measure theairflow rate of the air in holding cabinet 100. As indicated above,these measurements may be performed in any order, or even concurrently,and certain of the measurements may be omitted in some configurations.Humidity sensor 304, air temperature sensor 302, and airflow sensor 306can be configured to transmit the measured values of humidity,temperature, and airflow rate, respectively, to controller 200.

Thereafter, controller 200 may compare the measured values of humidity,temperature, and airflow rate with the respective values or ranges ofhumidity, temperature, and airflow rate corresponding to the selectedset point value. For example, when it is determined that the measuredhumidity is greater than the humidity value (or the upper limit of thehumidity range, when ranges are provided) corresponding to the selectedset point or that the measured temperature is greater than thetemperature value (or the upper limit of the temperature range, whenranges are provided) corresponding to the selected set point, controller200 may control the heaters, steam generator, and vents to regulateaccordingly. Conversely, for example, when it is determined that themeasured humidity is less than or equal to the humidity value (or thelower limit of the humidity range, when ranges are provided)corresponding to the selected set point or that the measured temperatureis less than or equal to the temperature value (or the lower limit ofthe temperature range, when ranges are provided) corresponding to theselected set point, controller 200 may control the heaters steamgenerator, and vents to regulate accordingly. Further, controller 200may change one or more of the frequency and duration (e.g., the dutycycle) of activating and deactivating the heaters, steam generator, andvents based on the deviation of the measured values from the values (orrange limits) corresponding to the set point value.

In addition, controller 200 may selectively control fan or blower 157,such that the airflow rate in holding cabinet 100 is selectively changedbased on a result of the comparisons. For example, when it is determinedthat the measured temperature is greater than the temperature value (orthe upper limit of the temperature range, when ranges are provided)corresponding to the selected set point or that the measured airflowrate is less than the airflow rate (or the lower limit of the airflowrate range, when ranges are provided) corresponding to the selected setpoint, controller 200 can be configured to activate fan or blower 157 orincrease the speed of fan or blower 157 in proportion to the deviationof the measured values from the values (or range limits) correspondingto the set point value. Conversely, for example, when it is determinedthat the measured temperature is less than or equal to the temperaturevalue (or the lower limit of the temperature range, when ranges areprovided) corresponding to the selected set point or that the measuredairflow rate is greater than the airflow rate (or the upper limit of theairflow rate range, when ranges are provided) corresponding to theselected set point, controller 200 can be configured to deactivate fanor blower 157 or decrease the speed of fan or blower 157 in proportionto the deviation of the measured values from the values (or rangelimits) corresponding to the set point value. Further, controller 200may change one or more of the frequency and duration (e.g., the dutycycle) of activating and deactivating fan or blower 157 based on thedeviation of the measured values from the values (or range limits)corresponding to the set point value.

Further, for example, when it is determined that the measuredtemperature is greater than the temperature value (or the upper limit ofthe temperature range, when ranges are provided) corresponding to theselected set point or that the measured airflow rate is less than theairflow rate (or the upper limit of the airflow rate range, when rangesare provided) corresponding to the selected set point, controller 200can be configured to control one or more of the heaters to deactivate orto generate less heat. Conversely, for example, when it is determinedthat the measured temperature is less than or equal to the temperaturevalue (or the lower limit of the temperature range, when ranges areprovided) corresponding to the selected set point or that the measuredairflow rate is greater than the airflow rate (or the upper limit of theairflow rate range, when ranges are provided) corresponding to theselected set point, controller 200 can be configured to control one ormore of the heaters to activate or to generate more heat. The amount ofheat generated by the heaters may be proportional to the deviation ofthe measured values from the values (or range limits) corresponding tothe set point value, and may be further informed by the measured airflowrate (e.g., when the measured airflow rate is high, there may be moreconvective cooling of the product and the vents may not need to beopened as far to reduce the temperature). Further, controller 200 maychange one or more of the frequency and duration (e.g., the duty cycle)of activation of one or more of the heaters based on the deviation ofthe measured values from the values (or range limits) corresponding tothe set point value.

Controller 200 may also determine whether the holding process iscomplete. When controller 200 determines that the holding process is notcomplete (e.g., when there is no indication that the holding process iscomplete), the environmental control process continues. In this manner,controller 200 may implement a feedback loop that controls theenvironmental conditions within holding cabinet 100 by periodicallymonitoring the humidity of air in holding cabinet 100, the temperatureof air in holding cabinet 100, and the airflow rate in holding cabinet100, which helps to maintain or reduce the degradation of the quality ofthe held product over an extended period of time. When controller 200determines that the holding process is complete, controller 200 may endthe holding process and the environmental control process may end.

While the invention has been described in connection with preferredembodiments, it will be understood by those of ordinary skill in the artthat other variations and modifications of the preferred embodimentsdescribed above may be made without departing from the scope of theinvention. Other embodiments will be apparent to those of ordinary skillin the art from a consideration of the specification or practice of theinvention disclosed herein. The specification and the described examplesare considered as exemplary only, with the true scope and spirit of theinvention indicated by the following claims.

1. A holding cabinet, comprising: a body defining a holding space; aholding compartment disposed within the holding space and configured tohold a product therein; a heating source comprising one or more of: aradiant heater disposed above the holding compartment, a conductionheater disposed below the holding compartment, and a convection heaterdisposed at an end of the holding compartment; a steam generator inatmospheric communication with the holding compartment and configured togenerate steam; a temperature sensor disposed adjacent to the holdingcompartment and configured to measure an air temperature of the holdingcompartment; a humidity sensor disposed adjacent to the holdingcompartment and configured to measure a relative humidity of the holdingcompartment; a product detector configured to detect that a product isloaded in the holding compartment and to identify a type of the product;a fan disposed adjacent to the heating source; an airflow sensordisposed within the holding space and configured to measure a rate ofairflow; and a controller configured to regulate environmentalconditions of the holding compartment according to a determinedsetpoint, which corresponds to a predetermined temperature and relativehumidity, by: acquiring the air temperature sensed by the temperaturesensor, the relative humidity sensed by the humidity sensor, and thetype of product detected by the product detector; activating anddeactivating one or more of the radiant heater, the conduction heater,the convection heater, and the steam generator in accordance with theacquired air temperature, the acquired relative humidity, and thedetermined setpoint corresponding to the type of product detected and aholding time of the product, to maintain the air temperature and therelative humidity of the holding compartment within a predeterminedrange based on the determined setpoint; and activating and deactivatingthe fan in accordance with the measured rate of airflow, the acquiredair temperature, the acquired relative humidity, and the determinedsetpoint corresponding to the type of product detected and a holdingtime of the product, to maintain the airflow, the air temperature, andthe relative humidity of the holding compartment within a predeterminedrange based on the determined setpoint.
 2. (canceled)
 3. The holdingcabinet according to claim 1, wherein the controller is configured toactivate a hold timer that measures the holding time and begin toregulate environmental conditions of the holding compartment in responseto the product detector detecting that a product is loaded in theholding compartment.
 4. The holding cabinet according to claim 1,further comprising: a product tray configured to hold product therein,wherein the holding compartment is configured to hold the product tray.5. The holding cabinet according to claim 4, wherein the holdingcompartment is configured to hold one or more product trays and each ofthe respective one or more product trays has a corresponding conductiveheater and radiant heater.
 6. The holding cabinet according to claim 4,wherein the holding cabinet comprises a plurality of the holdingcompartments and each of the respective plurality of the holdingcompartments are configured to hold one of the product trays.
 7. Theholding cabinet according to claim 1, further comprising: a doorconfigured to open and close to allow access to the holding compartment;and a switch adjacent to the door configured to be activated anddeactivated when the door is opened and closed, wherein the controlleris configured to detect when the door is open and closed based on theswitch, and to activate the heating source and the steam generator tomaintain the air temperature and the relative humidity at the determinedsetpoint.
 8. The holding cabinet according to claim 1, wherein thecontroller is configured to regulate environmental conditions of theholding compartment according to a plurality of the determinedsetpoints, each of the plurality of the determined setpointscorresponding to the predetermined temperature and relative humidity ata respective time during the holding time.
 9. The holding cabinetaccording to claim 1, wherein the product detector comprises an imagecapture device configured to capture an image and the controller isconfigured to detect that the product is loaded in the holdingcompartment and to identify the type of the product based on thecaptured image.
 10. The holding cabinet according to claim 4, whereinthe product detector comprises one or more of: a mechanical detectionmechanism disposed on the product tray, an optical detection mechanismdisposed on the product tray, and a radio frequency identificationdevice disposed on the product tray, wherein the controller isconfigured to detect that the product is loaded in the holdingcompartment and to identify the type of the product based on a readingfrom the one or more of the mechanical detection mechanism, the opticaldetection mechanism, and the radio frequency identification device. 11.A method for regulating environmental conditions of a holding cabinet,comprising: sensing an air temperature in the holding cabinet with atemperature sensor; sensing a relative humidity in the holding cabinetwith a humidity sensor; detecting a type of product in the holdingcabinet with a product detector; according to a determined setpoint,which corresponds to a predetermined temperature and relative humidity,activating and deactivating one or more of a radiant heater, aconduction heater, a convection heater, and a steam generator inaccordance with the sensed air temperature, the sensed relativehumidity, and the determined setpoint corresponding to the type ofproduct detected and a holding time of the product, to maintain the airtemperature and the relative humidity within a predetermined range basedon the determined setpoint; and activating and deactivating a fan inaccordance with a rate of airflow measured by an airflow sensor, thesensed air temperature, the sensed relative humidity, and the setpointcorresponding to the type of product detected and a holding time of theproduct, to maintain the airflow, the air temperature and the relativehumidity within a predetermined range based on the determined setpoint.12. (canceled)
 13. The method according to claim 11, further comprising:detecting that a product is loaded in the holding cabinet with theproduct detector; and activating a hold timer that measures the holdingtime and beginning to regulate environmental conditions of the holdingcabinet in response to the detecting that the product is loaded.
 14. Themethod according to claim 11, further comprising: detecting when a doorof the holding cabinet is open and closed based on a door switch; andactivating the one or more of the radiant heater, the conduction heater,the convection heater, and the steam generator to maintain the airtemperature and the relative humidity at the determined setpoint. 15.The method according to claim 11, further comprising: regulatingenvironmental conditions of the holding cabinet according to a pluralityof the determined setpoints, each of the plurality of the determinedsetpoints corresponding to the predetermined temperature and relativehumidity at a respective time during the holding time.
 16. The methodaccording to claim 11, further comprising: detecting that the product isloaded in the holding compartment and identifying the type of theproduct based on one or more of: an image captured by an image capturedevice, a reading from a mechanical detection mechanism, a reading froman optical detection mechanism, and a reading from a radio frequencyidentification device.
 17. A computer readable program product storinginstructions that, when executed by a processor, instruct the processorto perform processes comprising: sensing an air temperature in theholding cabinet with a temperature sensor; sensing a relative humidityin the holding cabinet with a humidity sensor; detecting a type ofproduct in the holding cabinet with a product detector; according to adetermined setpoint, which corresponds to a predetermined temperatureand relative humidity, activating and deactivating one or more of aradiant heater, a conduction heater, a convection heater, and a steamgenerator in accordance with the sensed air temperature, the sensedrelative humidity, and the determined setpoint corresponding to the typeof product detected and a holding time of the product, to maintain theair temperature and the relative humidity within a predetermined rangebased on the determined setpoint; and activating and deactivating a fanin accordance with a rate of airflow measured by an airflow sensor, thesensed air temperature, the sensed relative humidity, and the setpointcorresponding to the type of product detected and a holding time of theproduct, to maintain the airflow, the air temperature and the relativehumidity within a predetermined range based on the determined setpoint.